The on-wall M22s are a shade under 12 pounds, which is lighter than the QS8.
I have my QS8s mounted on drywall using only anchors - no studs. Even worse, one of my walls isn't even drywall - it's 1/4 inch particle press board, with very little for the screws to grab on to. I installed anchors and a couple of molly-type bolts in the T-Bracket. Both are holding up beautifully.
Just make sure to put a screw in every hole on teh T-Brackets to spread out the torque and shearing forces of the speakers.
And also, don't go jiggling those things around once they are on the wall ...
